1. Field of the Invention
This invention relates to slide fasteners having continuous coupling elements secured within folded edges of support tapes with head portions of the continuous coupling elements protruding through openings in the folded edges.
2. Description of the Prior Art
In commercially available slide fasteners utilizing continuous coupling elements such as spiral coupling elements secured to inner edges of carrier or support tapes, the continuous coupling elements are generally secured to the inner edges of the tapes by sewing or weaving the coupling elements to the tapes. The prior art, as exemplified in U.S. Pat. Nos. 1,557,303; 1,609,487; 1,933,290; 1,937,297; 2,018,099; 2,296,880; 3,430,304 and 3,517,422 and French Pat. No. 1,135,269 discloses a number of slide fasteners having continuous coupling elements secured within folded edges of a support tape wherein head portions of the coupling elements protrude from slots extending perpendicular across the folded edge of the support member. Additionally French Pat. No. 452,527 discloses a fastener with a spiral secured by strips of material formed at an angle across a folded edge of the strip. The commercial employment of slide fasteners with the continuous coupling elements secured in the fold of a tape has not been significant compared to fasteners with the coupling elements woven or sewn to textile tapes despite the obvious cost advance of low cost strips such as synthetic polymer or paper strips compared to woven textile tapes. This failure can be attribed to deficiences in the prior art, such as breakage or tearing of the strap portions of the support member, instability of the coupling element, inability to withstand high slider forces, excessive difficulty in slider operation, etc. Various other types of slide fasteners have been disclosed, such as U.S. Pat. No. 3,474,505 wherein a helically wound element is secured in abutting relationship to one edge of a tape by two threads, one of which extends through the tape and around the support portions of the element; also this U.S. Pat. No. 3,474,505 discloses a pair of cords on the opposite sides of the tape edge secured by the two threads to form a bead.